TD's on a bladder?

Do the TD's come with a fine NVA and a course thread? Or is the fine needle aftermarket like from Texas Timer? Thanks Ron!

TD's come stock with a regular NVA. There was a fine NVA in the kit when I had it, probably a Texas Timer's NVA.  

Phil

I think the fine needle is with the TE. I'm thinking of running some personal TD's on a bladder also. Thanks.

Along with the fine thread NV, a bored venturi makes a big difference too. I forgot to bore the venturi on the TD on my Li'l Satan when I first bolted it on. After I swapped it out to one bored with a 9/64 bit and polished, it really woke it up. .140" is the standard Paul Gibeault wrote of in a post in 2011. 9/64" is .1406, so that's about right. If you can't drop a 1/8" drill bit through it, then it has not been bored.

If you jam one ot those Fourmost check valves in its tail, then fueling is quick and easy. See it in the tail of my bladder in the pic:

Rusty

The TE has both a standard and a fine needle. I used the standard needle for the balloon tank.

The Atmospheric Mark

A stock bore is so much easier to start than bored out. There is a limit to how open the bore can get and the engine still be cooperative. Yes, livening up due to more air and more fuel is a wonderful thing. If it don't start with a "normal" amount of fuss it probably is opened up too much.

I was seriously ready to throw the towel in on TD's due to all my examples arriving with oversize venturies. Switching to stock, with fine NVA and pressure bladder made the engines a pleasure to operate. Set up this way they make plenty of power for my needs.

I can always bore out a venturi if I feel I need the added power, so I am not truly committed. When I got the oversize intake engines to start, BOY HOWDY did they run! It was just the hour of messing about between flights to get them TO start that was ruining the experience.

Phil

Too much bore will not only reduce friction loss of air/fuel mixture - which has a positive impact on the charge - but its reduced speed will reduce the depression in the venturi and thus the sucking capability of the engine. I think a fair polishing is what is worth doing but increasing the venturi bore may cause starting difficulties.

I run bladder pressure exclusively in combat. A venturi is not needed at all assuming the correct bladder material is being used. Kirn Kraft made this assembly for the TD. This assembly allows for a venturi throat of .220". They also provided a 128tpi spraybar and bracket which fit the Cox mag pan. This is what Dale Kirn used on his Spullet. Owning this myself I have not experienced one bit of starting problem as a result of using a large venturi.  Approximately .156" is the max on a Cox stock venturi due to breaking out and into the sprinkler holes. If one is experiencing issues from a drilled out venturi I would seriously take a closer look at those holes being damaged from drilling them. A venturi is not required to run bladder pressure.       Combat Albert was selling this Kirn Kraft part in some of his Ebay auctions. I find it just as easy to make a similar part using a burnt out glow plug. I drill out the post and drill into one of the flats of the hex and solder in a piece of 3/32" tubing.

LA.25 no venturi